My son got a radar ticket for going 85 in a 65 zone last week. We all figured he was just making excuses when he said he was watching his speedometer show 65, but then a few days later he passed a friend on the highway who called him and said he was flying. They paced each other for a few miles and discovered that in fact my son's speedo IS WAY off. Then I got thinking that his axle was replaced a while back; the original was a limited slip and since the mechanic couldn't find a replacement at an affordable price, he replaced it with a non LSD axle. He mentioned the ratio was a different, but not much, but now I'm beginning to wonder.

So, three questions for the Collective Wisdom:

1) Anyone know what the ratio was for the limited slip (this is an '84 GLT with manual transmission)?

2) How about the ratio for the non-LSD axle? (Unfortunately, I don't know what year the donor car was--did they vary?)

3) Any ideas for how to convince the court that it was a mechanical problem? Does anyone "calibrate" speedos these days? (I'm prety sure the '84 has a mechanical cable to the tranny rather than an electronic speedo)

He's looking a 6-point ticket, so he'll really appreciate advice!!